The “Polar Light Sign” is a useful tool to detect discrete membranous supravalvular mitral stenosis

Abstract

Mitral valve stenosis caused by a discrete supravalvular membrane is a rare congenital malformation haemodynamically leading to significant mitral valve stenosis. When the supravalvular mitral stenosis consists of a discrete supravalvular membrane adherent to the mitral valve, it is usually not clearly detectable by routine echocardiography. We report about the typical echocardiographic finding in three young patients with this rare form of a discrete membranous supravalvular stenosis caused by a membrane adherent to the mitral valve. These cases present a typical echocardiographic feature in colour Doppler generated by the pathognomonic supramitral flow acceleration. Whereas typical supravalvular mitral stenosis caused by cor triatriatum or a clearly visible supravalvular ring is easily detectable by echocardiography, a discrete supravalvular membrane adjacent to the mitral valve leaflets resembling valvular mitral stenosis is difficult to differentiate by routine echocardiography. In our opinion, this colour phenomenon does resemble the visual impression of polar lights in the northern hemisphere; owing to its typical appearance, it may therefore be named as "Polar Light Sign". This phenomenon may help to detect this anatomical entity by echocardiography in time and therefore improve the prognosis for repair.

Supravalvar mitral ring with a parachute mitral valve and subcoarctation of the aorta in a child with hemodynamically significant VSD. A study of the morphology, echocardiographic diagnostics and surgical therapy

“…The presurgical diagnosis is extremely important in case of the coexistence with another hemodynamically significant defect, e.g. VSD, which – as in the presented case – constitutes the main indication for cardiac surgical correction ( 4 , 5 ) . The approach through the opening of the anterior wall of the right atrium which is applied for the closing of the ventricular septal defect, does not allow for the surgical visualization of the interior of the left atrium nor of the mitral valve and thus does not allow for the intraoperational verification of the diagnosis and for broadening the scope of the intervention.…”

“…The name of the defect suggests the existence of a pathological excrescence located completely in the left atrium, over the mitral ring. However, there are reports of various spatial relationships of the membrane towards the valve: it may be located inside the atrium (completely over the ring), in the intermediate position (over the mural leaflet and on the atrial surface of the aortic leaflet) or it may be completely connected with the leaflets ( 2 , 4 ) . This last location seems to be the most logical one because the suggested background for the formation of the membrane is incorrect division of the mesenchymal tissue of the pericardial cushions ( 1 , 3 , 5 ) .…”

Tetralogy of Fallot associated with supramitral ring: “Paying for a near miss”

“…Echocardiographic evaluation is incomplete without mitral valve without color Doppler interrogation. The echocardiographic diagnosis of SMR is highly suggestive when color flow (mosaic) and pulse wave Doppler acceleration are maximum just before mitral valve on left atrial side [7]. We looked into the preoperative echocardiogram, but neither the mitral valve apparatus was well focused nor the mitral inflow was interrogated with color Doppler.…”

Mid-Term Results of Congenital Supravalvar Mitral Ring Resection

“…When concomitant VSDs are present, delineating the SMR may be difficult due to the left to right shunt . A typical color phenomenon, which is defined as “Polar Light Sign” may be useful in echocardiographic diagnosis of such cases . When the left‐sided obstructive pathologies—especially the Shone's complex—is considered, the detection of SMR is crucial in order to prevent residual defects after the surgical intervention .…”

“…7 A typical color phenomenon, which is defined as ''Polar Light Sign'' may be useful in echocardiographic diagnosis of such cases. 8 When the left-sided obstructive pathologies-especially the Shone's complex-is considered, the detection of SMR is crucial in order to prevent residual defects after the surgical intervention. 9 In our series, we operated on two patients with Shone's complex in which additional interventions were performed at the sub-aortic, supraaortic level or the aortic valve itself.…”